The present invention relates to a pushbutton drive for key contacts in which a mushroom button is loaded by a restoring force. More particularly, the drive is of the type in which the stem of the mushroom button is guided movably in a housing and is provided with a rest position, and an operating position detent which can be released through rotation of the mushroom button.
In one known pushbutton drive of the above-described type, a tangible counterforce is overcome when the mushroom button is operated in going from one switch position to another switch position in which the drive becomes latched. After a pressure point is passed, the required force becomes smaller, and the switching process from the one switch position to the other latched switch position takes place automatically with a jump action or characteristic. In such a pushbutton drive, the latched position, for example the operating position detent, can be released by rotation of the mushroom button with the mushroom button returning automatically to the rest position. Basically, this type of pushbutton drive meets the requirements of the trade associations and the Technical Surveillance Association with respect to detection of use if the mushroom button is merely pressed down, since a jump characteristic is obtained by a suitable detent in going from the one switch position to the other latched switch position, as mentioned. If the mushroom button is turned, however, in the release direction before it is pressed down, then the switch can go from one switch position to the other switch position without latching, and detection of use is not possible. For example, an emergency "off" switch can be opened without the pushbutton drive going into the latched operating position.